Experimental study of the SLM behavior and remote sensing applications of a multi-wavelength fiber laser topology based on DWDMs

Abstract

microwave photonics [1]. Several approaches have been employed to implement SLM operation in EDFLs, such as short linear cavity distributed Bragg reflector fiber lasers, fiber distributed feedback lasers, fiber ring lasers or Sagnac configurations [2,3] with different ring cavity topologies. However, the fiber ring laser unavoidably generates an enormous number of densely spaced longitudinal modes lying beneath the erbium gain profile due to the required intracavity optical components, connecting fibers, and a rather long cavity length. Thus, fiber ring lasers usually perform unstably with a larger linewidth due to the multimode oscillation, mode competition, and hopping. Several previous studies proposed by the authors [2,4] show that a single-mode operation of these laser systems in the C-band can be achieved when we emit simultaneously more than one wavelength using special ring cavity configurations.On the other hand, the utilization of CWDM techniques in sensors multiplexing enhances the power budged, and scalability of the network is possible in combination with DWDM techniques or ordinary couplers as stated in [5,6].Optical amplification techniques, and particularly, doped fiber amplifiers supposed a revolution for optical fiber systems [7]. Moreover, the use of Raman amplification also enabled the remote sensor operation, increasing the number of sensors per fiber on the network [7-9]. The optimum configuration of the amplifier employed in a sensor network strongly depends on the system topology, the number of sensors and the multiplexing technique [10].Investigation in remote sensing is under way with a few approaches of ultra-long-distance fiber Bragg gratings sensor systems using tunable filters or different interrogation techniques which reach as far as 250 km [11]. However, these systems have restrictive multiplexing capabilities (e.g., sensors can be located only at the end of the fiber) and do not allow a real-time monitoring. This is because Abstract In this work, two different multi-wavelength fiber ring laser configurations have been proposed and experimentally demonstrated. The aim of this paper is to show the versatility of the MUX/DMUX device for designing fiber lasers. That was carried out by enhancing the performance of two intrinsically different fiber lasers: an EDF in single longitudinal-mode (SLM) operation and an ultralong cavity multi-wavelength Raman laser for remote sensing applications. The main objective of the first experimental setup is to generate SLM emission lines with linewidths as narrow as possible. That was carried out by using the interaction between the reflected signals from the FBGs and the transmitted signal from the corresponding PS-FBG in each transmission band. The second topology consists of a multi-wavelength fiber laser for remote sensing applications by using Raman amplification where sensors located 100 km away from the receiver have been measured. As a remarkable improvement from other remote sensing systems, the sensors can be located at any place of the fi...

Narrow-Linewidth Multi-Wavelength Random Distributed Feedback Laser

“…The MUX/DMUX has four 200 GHz-wide channels (ITU channels C31, C35, C41 and C47) with insertion losses of 1.8-2.2 dB per channel. This device permits the inclusion of a variable attenuator (VA) in every branch to independently control the losses of each channel, adding the lowest possible losses to the cavity as reported in [24]. In this case, the PS-FBGs are concatenated in a serial configuration.…”

High Performance Fiber Laser Resonator for Dual Band (C and L) Sensing

“…Nevertheless, achieving this generally comes at the expense of a substantial increase in the cost and complexity of the cavity. For instance, using saturable absorbers implies the insertion of passive EDF sections in the resonator [12]; power equalization between lines must be guaranteed in self-injection lasers [13]; and the introduction of fiber Bragg gratings (FBGs) in combination with narrow phase-shifted FBGs (PS-FBGs) in the cavity hinders their use as a sensor system [14]. A solution that seems to be emerging at the moment is to assist the laser emission by means of reflectors in which the backscattering is artificially and pseudo-randomly increased along short fiber sections.…”

Single longitudinal mode fiber ring laser

“…Several works on multi-wavelength fiber lasers have been published in the last years, partly because of their great potential for some applications like microwave photonics systems, fiber-optic sensors, spectroscopy and wavelength division multiplexed systems [1,2,3]. A configuration of erbium-doped fiber 5 ring laser is an interesting choice to generate a multiple wavelength output due to its good compatibility with other optical fiber components, high gain and low noise figure.…”